Device for shaping of helical fins on the outer wall of a tube

Abstract

A device for the formation by rolling of helical fins on heat exchange tubes to increase the heat transfer capacity of the tubes. The device comprises four forming rolls (6, 7, 8, 9) which are arranged on two carriages (4, 5) which are moved together in translation fashion by a hydraulic jack which enables the four forming rolls to bear simultaneously on the wall of a tube (2). The four forming rolls operate around the tube and are rotatably driven at equal speed by a single motor (50). The forming rolls are oriented about an axis (X2, X4, X5) which is perpendicular to the fin shaping zone. The tube (2) is driven by the forming rolls along an axis of translation.

What is claimed is: 
     
       1. A device for the forming of at least one helical fin (3) on the outer wall of a tube (2) comprising: first and second carriages (4, 5) arranged opposite each other symmetrically in a shaping zone on either side of the tube, the axis of the tube defining an axis of translation (XI--XI),   translation means for moving said first and second carriages to approach each other to a working position and for moving apart from each other,   each of said first and second carriages having a pair of carrier heads (10, 11), (12, 13),   each carrier head including a forming roll (6, 7, 8, 9), a carrier shaft (18, 19, 20, 21), a drive shaft (24, 25, 26, 27) for driving said carrier shaft and thus rotating the forming roll,   rotary transmission means (22, 23)   motor means (50),   said motor means driving the transmission means and said transmission means driving each drive shaft at the same speed,   each of said carrier heads having its orientation axis (X2, X3, X4, X5) and being movable about its axis, and   said carrier heads being arranged so that the relative angle formed between the orientation axes is 90, the orientation axes intersecting the tube shaping zone when the forming rolls are in working position.   
     
     
       2. A device according to claim 1 wherein the means for translation of the two carriages (4, 5) makes it possible for these carriages to be brought towards each other or moved away from the axis of translation (XI) of the tube (2) is at least one jack having a cylinder (31) which is integral with the first of the carriages (4), a rod (33) of at least one piston (32) being connected to the second of the carriages (5). 
     
     
       3. A device according to claim 1 or claim 2 further including means for synchronising the translation of the carriages (4, 5) having a swinging beam (34) mounted to a fixed pivot, the vertical axis (X6 of which intersects the axis of translation (XI--XI) of the tube, the ends (35B, 36B) of the beam each being connected by means of a rigid rod (35, 36) to an end (35A, 36A) of each carriage (4, 5). 
     
     
       4. A device according to claim 2 additionally comprising means for accurate adjustment of the end of the travel of said at least one piston (32) of said jack, the accurate adjustment means including closure means (41) for the pipe (42) supplying the cylinder (31) of the jack with high pressure fluid, said closure means cooperating with the rod (33) and the piston (32) of the jack, and a control means (39) permitting accurate adjustment of the length of the travel of the rod (33) of the piston (32), the closure means operating to interrupt high pressure fluid supply to the cylinder. 
     
     
       5. A device according to one of claims 1 or 2 wherein each forming roll carrier shaft (18, 19, 20, 21) is perpendicular to the corresponding axis of orientation (X2, X3, X4, X5) which it intersects. 
     
     
       6. A device according to one of claims 1 or 2 wherein each forming roll carrier shaft (18, 19, 20, 21) and the corresponding drive shaft (24, 25, 26, 27) are mounted on a forming roll carrier head (10, 11, 12, 13) which bears against the tool carrier end (4-1, 5-1) of a carriage (4, 5) by virtue of a bearing surface (14, 15, 16, 17) which surface is perpendicular to the corresponding axis of orientation (X2, X3, X4, X5), and a means for angular setting (72, 73) enabling each forming roll carrier head to rotate a few degrees about its axis of orientation. 
     
     
       7. A device according to claim 6 further including setting means for the forming roll carrier head (10, 11, 12, 13) to displace the forming roll carrier head along its axis of orientation. 
     
     
       8. A device according to claim 7 wherein said setting means is introduced into the bearing surface (14, 15, 16, 17) and the angular position of the forming roll about the tube is adjusted to 90°. 
     
     
       9. A device according to claim 6 wherein each forming roll carrier head (10, 11, 12, 13) comprises a detachable part (90) inside which is accommodated at least one bearing of the forming roll carrier shaft, this detachable part, when dismantled, permitting removal and, if necessary, replacement, of the forming roll (6, 7, 8, 9). 
     
     
       10. A device according to one of claims 1 or 2 wherein each of the drive shafts (24, 25, 26, 27) is connected with said motor means (50) by transmission means including a telescoping shaft (57, 58) which is pivotally connected to each drive shaft. 
     
     
       11. A device according to claim 10 wherein the transmission means between the motor means (50) and the drive shafts (24, 25, 26, 27) also comprise a toothed rim wheel (53) through which the axis of translation (X1--X1) of the tube (2) passes, said toothed rim wheel is being driven by a toothed pinion (52) which is connected to the motor means (50) and the toothed rim wheel is driving four toothed pinions (55, 56 which are disposed at 90° relative to each other about the axis of translation (X1--X1), each pinion driving a telescoping shaft (57, 58). 
     
     
       12. A device according to one of claim 1 or 2 wherein each forming roll (6, 7, 8, 9) is constituted of a plurality of discs of revolution (61, 62, 63, 64, 65) having the same axis as the forming roll carrier shaft (18, 19, 20, 21), the side of each forming roll being oriented towards the smooth upstream part of the tube (2) which is to be provided with fins comprising at least one disc (61, 62, 63) which is less in diameter than a following disc, the forming roll being held to its forming roll carrier shaft by at least one axial setting means which allows the axial position of the forming roll to be adjusted on the corresponding forming roll carrier shaft relative to that of the other forming rolls. 
     
     
       13. A device according to one of claims 1 or 2 wherein the wall of the tube (2), during the operation of providing it with the fins, is held in the shaping zone by an internal mandrel (82) of appropriate frustoconical shape, said mandrel being connected to the retaining rod (83), an upstream end of this retaining rod itself being attached to a fixed point situated beyond the upstream end of the tube (2). 
     
     
       14. A device according to claim 13 wherein the mandrel (82) is mounted to freely rotate about the axis of translation (X1--X1). 
     
     
       15. A device according to claim 1 wherein the tube (2) is supported, along the axis of translation (X1--X1), by channels which are covered, at least for the length of the tube with a fin, with a layer of plastic material. 
     
     
       16. A device according to claim 1 wherein at least one drive roller engages the tube (2) in the forming rolls prior to the operation during which the tube (2) is provided with fins. 
     
     
       17. A device according to claim 16 wherein a group of proximity detection means is provided, such proximity detection means being connected to electronic means which operate to set in motion or to interrupt the operation of fin generation so that predetermined tube zones are not provided with a fin. 
     
     
       18. A device according to claim 17 wherein the detection means is connected to the electronic means by way of a bus bar which permits a very large number of connections to be made and which thus allows a plurality of finned zones and non-finned zones to be formed on the tube. 
     
     
       19. A device according to claim 18 wherein starting of the fin-providing operation is controlled by the electronic means, so that after placement of a smooth tube (20), the setting in motion of the forming rolls which are disposed at a spacing away from the axis of translation (X1--X1) occurs at a reduced operating speed, then setting in motion the jack in order to gradually bring the forming rolls (6, 7, 8, 9) closer to the wall of the tube (2) until each forming roll gradually increases pressure against the wall of the tube (2), then automatically stopping operation of the jack by means of closure of the high pressure fluid intake and gradually increasing the speed of rotation of the forming rolls until a normal operating speed is reached. 
     
     
       20. A device according to claim 18 wherein the operation of providing the tubes with fins is stopped by a group of proximity detection means which decelerates the speed of rotation of the forming rolls, and then actuates the return piston (37) so as to move the carriages (4, 5) away from the axis (X1--X1) and interrupts rotation of the forming rolls. 
     
     
       21. A device according to claim 17 wherein starting of the fin-providing operation is controlled by the electronic means, so that after placement of a smooth tube (20), the setting in motion of the forming rolls which are disposed at a spacing away from the axis of translation (X1--X1) occurs at a reduced operating speed, then setting in motion the jack in order to gradually bring the forming rolls (6, 7, 8, 9) closer to the wall of the tube (2) until each forming roll gradually increases pressure against the wall of the tube (2), then automatically stopping operation of the jack by means of closure of the high pressure fluid intake and gradually increasing the speed of rotation of the forming rolls until a normal operating speed is reached. 
     
     
       22. A device according to claim 17 wherein the operation of providing the tubes with fins is stopped by a group of proximity detection means which decelerates the speed of rotation of the forming rolls, and then actuates the return piston (37) so as to move the carriages (4, 5) away from the axis (X1--X1) and interrupts rotation of the forming rolls. 
     
     
       23. A device according to claim 1 or 2 further comprising proximity detection means disposed along the axis of translation (X1--X1) at pre-determined spacings from the shaping zone to provide a signal indicating the passage of the tube front end. 
     
     
       24. A device according to claim 1 wherein said motor means (50) comprises a single direct current motor of variable speed and high starting torque.